Wound pressure determination for reduced pressure wound therapy

Abstract

Embodiments of a negative pressure wound therapy systems and methods for operating the systems are disclosed. In some embodiments, a system includes a pump assembly, canister, and a wound dressing configured to be positioned over a wound. The pump assembly, canister, and the wound dressing can be fluidically connected to facilitate delivery of negative pressure to a wound. The pump assembly can present graphical user interface screens for controlling and monitoring delivery of negative pressure. The system can be configured to efficiently deliver negative pressure and to detect and indicate presence of certain conditions, such as low pressure, high pressure, leak, canister full, and the like. Monitoring and detection of operating condition can be performed by measuring one or more operational parameters, such as pressure, flow rate, and the like.

What is claimed is: 
     
       1. A negative pressure wound therapy apparatus comprising:
 a source of negative pressure configured to be fluidically connected by a fluid flow path to a wound dressing covering a wound, the source of negative pressure configured to aspirate fluid from the wound in accordance with a negative pressure set point; 
 a pressure sensor positioned in the fluid flow path and configured to measure a first pressure in the fluid flow path at a location away from the wound; and 
 a controller programmed to determine a second pressure at the wound based on combining the first pressure in the fluid flow path measured by the pressure sensor with a level of activity of the source of negative pressure and the negative pressure set point. 
 
     
     
       2. The apparatus of  claim 1 , wherein the controller is programmed to determine the second pressure at the wound based on subtracting a scaled level of activity of the source of negative pressure from the first pressure in the fluid flow path measured by the pressure sensor. 
     
     
       3. The apparatus of  claim 2 , wherein the scaled level of activity comprises the level of activity multiplied by a constant derived from the negative pressure set point. 
     
     
       4. The apparatus of  claim 1 , wherein the source of negative pressure comprises an actuator, and wherein the level of activity of the source of negative pressure comprises a level of activity of the actuator. 
     
     
       5. The apparatus of  claim 4 , wherein the actuator comprises a motor, and wherein the level of activity comprises speed of the motor. 
     
     
       6. The apparatus of  claim 1 , further comprising a tachometer configured to measure speed of a motor of the source of negative pressure, and wherein the level of activity comprises speed of the motor. 
     
     
       7. The apparatus of  claim 1 , wherein the pressure sensor is positioned in or near an inlet of the source of negative pressure. 
     
     
       8. The apparatus of  claim 1 , wherein the source of negative pressure comprises a diaphragm pump. 
     
     
       9. The apparatus of  claim 1 , further comprising a canister configured to store at least some fluid aspirated from the wound. 
     
     
       10. The apparatus of  claim 1 , further comprising an input interface configured to permit a user to adjust a target negative pressure to be provided by the source of negative pressure. 
     
     
       11. The apparatus of  claim 10 , wherein the input interface comprises a touch screen display. 
     
     
       12. The apparatus of  claim 1 , wherein the controller is programmed to determine the second pressure at the wound without using any measurements of pressure made directly at the wound. 
     
     
       13. A method of operating a negative pressure wound therapy apparatus, the method comprising:
 causing a source of negative pressure to aspirate fluid from a wound covered by a wound dressing in accordance with a negative pressure set point, the source of negative pressure configured to be fluidically connected to the wound dressing by a fluid flow path; 
 causing a pressure sensor positioned in the fluid flow path to measure a first pressure in the fluid flow path at a location away from the wound; and 
 determining a second pressure at the wound based on combining the first pressure in the fluid flow path measured by the pressure sensor with a level of activity of the source of negative pressure and the negative pressure set point, 
 wherein the method is performed under control of a controller of the negative pressure wound therapy apparatus. 
 
     
     
       14. The method of  claim 13 , wherein determining the second pressure at the wound comprises subtracting a scaled level of activity of the source of negative pressure from the first pressure in the fluid flow path measured by the pressure sensor. 
     
     
       15. The method of  claim 14 , wherein the scaled level of activity comprises the level of activity multiplied by a constant derived from the negative pressure set point. 
     
     
       16. The method of  claim 13 , wherein the source of negative pressure comprises a motor, and wherein the level of activity comprises speed of the motor. 
     
     
       17. The method of  claim 16 , wherein speed of the motor is measured by a tachometer of the negative pressure wound therapy apparatus. 
     
     
       18. The method of  claim 13 , wherein the pressure sensor is positioned in or near an inlet of the source of negative pressure. 
     
     
       19. The method of  claim 13 , further comprising receiving an adjusted target negative pressure via an input interface of the negative pressure wound therapy apparatus and causing the source of negative pressure to provide the adjusted target negative pressure. 
     
     
       20. The method of  claim 13 , wherein determining the second pressure at the wound is performed without using any measurements of pressure made directly at the wound.